The mainstay of Arunachal Pradesh’s economy is:

Agriculture
Tourism
Information Technology
Heavy Industries

The correct answer is: a) Agriculture.

Arunachal Pradesh is a state in northeastern India. It is the largest state in the country by area, but has the lowest population density. The economy of Arunachal Pradesh is based on agriculture, which employs about 70% of the workforce. The main crops grown in the state are rice, maize, millet, and wheat. Other important agricultural products include tea, ginger, and turmeric.

Tourism is also a major source of income for Arunachal Pradesh. The state is home to a number of beautiful natural attractions, including mountains, forests, and rivers. The government of Arunachal Pradesh has been promoting tourism in the state in recent years, and the number of tourists has been increasing steadily.

Information Technology and Heavy Industries are not major sectors of the economy of Arunachal Pradesh. There are a few IT companies and factories in the state, but they do not employ a large number of people.

In conclusion, the mainstay of Arunachal Pradesh’s economy is agriculture.